X-ray tube electrode mounting

ABSTRACT

The rotating anode structure of an X-ray tube is positioned relative to the tube&#39;&#39;s glass envelope by a deepdrawn cylindrical metal cup joined to a cylindrical portion of the glass envelope by a second cup. The rotating anode structure extends through the cup where it is secured to an X-ray tube housing and where it is connected to a source of anode voltage. The cup provides a metal grain structure for maintaining a gastight seal for the X-ray tube, while providing a stronger and more shock resistant tube construction.

0 United States Patent [1113,566,173

[ 1 Inventors a [56] References Cited 8 UNITED STATES PATENTS Gage" 2,170,695 8/1939 Pike 313/220x 2 Appl. No 75 7 9 2,341,483 2/1944 Stephen... 313/55 S p 3, Depcw Patented FebI 23, Zunick t al [73] Assignee Picker Corporation Primary Examiner-Roy Lake white n N.Y. Assistant Examiner- E. R. La Roche AttorneyBuckhorn, Blore, Klarquist and Sparkman ABSTRACT: The rotating anode structure of an X-ray tube is [54] MOUNTING positioned relative to the tubes glass envelope by a deepg drawn cylindrical metal cup joined to a cylindrical portion of [52] U.S. Cl. 3113/55, the glass envelope by a second cup. The rotating anode struc- 313/60, 313/220, 313/318 ture extends through the cup where it is secured to an X-ray [51] Int. Cl. ..H0lj 17/16, tube housing and where it is connected to a source of anode HOlj 35/16 voltage. The cup provides a metal grain structure for main- [50] Field of Search 313/55, 60, taining a gastight seal for the X-ray tube, while providing a stronger and more shock resistant tube construction.

X-RAY TUBE ELECTRODE MOUNTING BACKGROUND OF THE INVENTION X-ray tubes are conventionally constructed with a gastight glass envelope joined to an anode structure at one end and a cathode structure at the other. The tube envelope substantially encloses both anode and cathode, and is formed with reentrant cylindrical glass sections at each end joined by means of a glass-to-metal seal at the rear of the anode or cathode structure. While this manner of construction is adequate for many purposes, the reentrant portion of the envelope is subject to breakage, particularly in the case where the same is joined to heavy electrode structures affected by vibration. An example of such an electrode structure comprises a rotating anode and the rotor body therefor. Some attempts have been made to substitute metal constructions for the reentrant glass configuration, whereby the glass-to-metal seal is formed at the outer periphery of a cylindrical portion of the glass envelope. However, ordinary metal constructions as may be formed from machined rod, bar stock, or tubing, for example, frequently result in an X-ray tube envelope having other than the desired gastight seal properties.

SUMMARY OF THE INVENTION According to the present invention, the electrode structure for example the rotating anode structure in an X-ray tube, is positioned relative to a cylindrical glass envelope portion by a cylindrical metal portion or cup. This metal portion or cup preferably extends longitudinally from one end of the electrode structure, and further means are provided for joining the metal cup to the cylindrical portion of the envelope, e.g. by a glass-to-metal seal. Deep drawing of the metal cup and/or rolling of the sheet from which the cup is made provides a grain structure internal to the metal cup substantially perpendicular to the path which might otherwise be taken by air passing through the metal construction. This grain structure appears to block filamentary passages or the like, rendering the overall envelope gasti'ght. The gastightness is achieved while at the same time providing a tube construction of enhanced strength.

it is accordingly an object of the present invention to provide an improved X-ray tube electrode mounting for rendering an X-ray tube envelope less subject to breakage as a result of vibration, or the like.

it is another object of the present invention to provide an improved X-ray tube electrode mounting for enhancing the strength of an X-ray tube construction while at the same time maintaining a gastight seal for the overall X-ray tube envelope.

it is another object of the present invention to provide an improved means for mounting the rotor body of a rotating type anode in an X-ray tube relative to the glass envelope of the X-ray tube.

It is a further object of the present invention to provide an improved means for mounting and also for connecting certain DRAWING The single drawing is a fragmentary longitudinal cross section of an X-ray tube constructed in accordance with the present invention.

DETAlLED DESCRIPTION Referring to the drawing, the X-ray tube illustrated therein comprises an envelope 10 formed of glass (or equivalent insulating material) having a cathode 14 mounted at one end and an anode 16 mounted at the other. The anode 16 is of the rotary type and comprises a rotor body 18 suitably supported by nearing structure (not shown) upon a stem or spindle 20. Extending from the rotor body 18 towards cathode I4 is a shaft 24 which supports a target member or disc 26 secured to the shaft by cap nut 28. The target disc 26 is preferably formed of tungsten or another metal of high atomic number, and the nut 28 and shaft 24 are preferably formed of molybdenum or another suitable metal having high strength at high temperatures. As will be noted, the target disc 26 is formed with a peripheral bevel or frustoconical surface portion 30 and a flat center portion 32 which extends at right angles to shaft 24. The anode is suitably connected to ,a high positive potential by means hereinafter described which may, for example, maintain the anode at a voltage of approximately l50 kvp. with respect to the cathode.

The cathode 14 is provided with a head portion 34 having a conventional recessed focusing cup with a filament mounted therein (not shown). The cathode is designed to generate and focus a beam of electrons upon the target surface portion 30 of the rotating anode directly opposite head portion 34 of the cathode. As a result, X-rays are produced which pass through the glass envelope in a manner understood by those skilled in the art.

A stator indicated at 36 suitably surrounds extended cylindrical glass portion 38 of the envelope and supplies a magnetic field for driving the rotor 18. A cylindrical glass member indicated at 40 is interposed between cylindrical glass portion 38 and stator 36 for dielectric protection of the stator.

According the the present invention, the anode electrode structure, and specifically spindle 20 supporting rotor body 18, is positioned or supported with respect to cylindrical glass portion 38 of the envelope by means of a metal member preferably comprising a metal cup or cup-shaped portion 42. This cup 42, which is suitably formed of 42 percent nickel steel, includes a base or bottom portion 44 and a cylindrical sidewall portion 46. The bottom portion is provided with an aperture 48 through which a reduced diameter length of spindie 20 extends. The shoulder 50 of spindle 20 abuts bottom portion 44 of cup 42 and suitably is brazed thereto.

The cylindrical sidewall portion 46 of cup 42 extends longitudinally away from the central enclosure of the X-ray tube and defines a circular endopening 52. Near opening 52, the exterior of cup 42 is reduced in outside diameter to receive a second cup 56 thereupon, which may also be formed of 42 percent nickel steel. Cup 46 is apertured at 54 and closely received upon 42, the two cups suitably being heliarc welded together around their circular abutment. Cup 56 is larger in diameter than cup 42 and includes a base or bottom portion 58 in which aperture 54 is centrally located, and a cylindrical sidewall portion 60 extending coaxially back over cup 42, with a conventional glass-to-metal seal being provided at 62 between cylindrical glass portion 38 and sidewall portion 60. In this construction, the glass-to-metal is located at the diameter of cylindrical glass portion 38, and the conventional reentrant glass construction is avoided. As a result, the tube is much more shock resistant and less subject to breakage than the ordinary rotating anode X-ray tube utilizing a reentrant glass configuration.

Spindle 20 extends through aperture 48 and is tapped to receive a machine screw 64 extending through metal mounting bracket 66. Mounting bracket 66 includes a connecting arm section 72 provided with a plug portion 74 received in high voltage socket 76 for supplying an electrical connection to the X-ray tube anode. Thus, the bracket 66 including arm section 72 both supports the anode end of the X ray tube and provides the electrical connection for the anode. The rotating anode electrode structure is supported directly from bracket 66 while the glass envelope of the X-ray tube, and specifically the cylindrical portion 38 thereof, is supported directly through metal cups 12 and 56 for forming a heavier duty structure than has been heretofore available.

Metal portion or cup 42 is desirably formed of cold-rolled sheet material, and/or is deep drawn, being formed in one or more drawing operations from a metal blank in a press, the blank being forced through the bore of a die by a punch. As a result of a metal forming operation, metal flow takes place, e.g. resulting from circumferential compression around the sidewall of the cup and tension along the cup during a drawing operation. As the metal is permanently deformed beyond its elastic limit by the cold working, a slippage or rearrangement occurs along the slip planes within the metal crystals forming the cup. The cold working of the cup produces a distorted grain structure wherein the grain orientation is substantially perpendicular to the direction taken by air tending to leak through the cup, that is, perpendicular to the cylindrical surface of the metal cup. This grain structure, perpendicular to the surface of the cup, closes filamentary air passages which otherwise tend to exist through the bulk of the material. Therefore, the tube remains substantially gastight. The metal from which cup $2 is formed is preferably worked by coldrolling sheet material prior to the formation of the cup therefrom. in such case, the cup may be formed by spinning, while still retaining the airtight qualities imparted by rolling, since the rolling substantially prevents leakage in a direction perpendicular to the surface of the material. Cup 56 is desirably formed in the same way as cup d2.

It has been found that without employing this type of construction, as when a metal construction is formed with machined rod or tubing, leaks through the metal tend to appear after the tube is welded and exhausted. The above described, cold-worked, metal portion or cup provides a grain structure which is, in all critical areas, perpendicular to the fiow path of gases, whereby difficulties in maintaining a gastight structure are substantially reduced.

Although the present construction has been described principally in connection with mounting of an anode, and specifically the rotating anode structure in an X-ray tube where support problems are particularly severe, it will also be appreciated that the same construction 'may be employed at the cathode end of the tube.

While we have shown and described preferred embodiments of our invention, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from our invention in its broader aspects. We therefore intend the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

We claim:

1. An X-ray tube comprising an envelope enclosing a cathode electrode and an anode electrode therewithin, said envelope including a cylindrical glass portion, and electrode support structure extending within said cylindrical glass portion; i

a metal cup-shaped portion joined to said electrode support structure and extending longitudinally from a location proximate one end of said electrode support structure for positioning said electrode support structure relative to said envelope, said cup-shaped portion comprising coldworked metal having a distorted grain structure with a grain orientation substantially parallel to the surface of the cup-shaped portion; and

means joining said metal cup-shaped portion to the cylindrical glass portion of said envelope providing a seal with said cylindrical glass envelope portion, said cup-shaped portion cooperating to form an additional closed part of said envelope.

2. The X-ray tube according to claim 1 wherein said cupshgped portion is a deep drawn metal cup. I

. The X-ray tube according to claim 1 wherein said means joining said cup-shaped portion to the cylindrical portion of the envelope comprises a second cup of greater diameter than the first mentioned cup-shaped portion, being joined to the first mentioned cup-shaped portion proximate one end of said second cup and providing a glass-to-r netal seal with the cylindrical glass envelope portion at its other end.

4. The X-ray tube according to claim 1 wherein said cupshaped portion includes a bottom portion and a cylindrical sidewall portion, said electrode structure extending through and closing an aperture provided in said bottom portion; and support and connection means joined to said electrode structure on the remote side of said'bottom portion from the interior of said envelope.

5. The X-ray tube according to claim 1 wherein said cup-' shaped portion includes a bottom portion joined to said electrode structure and a cylindrical sidewall portion extending longitudinally away from said glass envelope portion defining an opening periphery at the remote end of said cup-shaped portion from said bottom portion; said means joining said cupshaped portion to said cylindrical glass portion of said envelope comprising a second cup larger in diameter than said first cup-shaped portion, said second cup being provided with a cylindrical sidewall portion and an apertured bottom portion where said second cup is heliarc welded to the sidewall portion of said first cup-shaped portion proximate to the end of said first cup-shaped portion farthest from said glass envelope portion, the cylindrical sidewall portion of said second cup extending toward said glass envelope portion and forming a glass-to-metal seal with said glass portion of said envelope.

6. The X-ray tube according to claim 5 wherein the bottom portion of the first cup-shaped portion is apertured with said electrode structure extending through and substantially filling said aperture, said electrode structure further extending coaxially of the sidewall portion of said first cupshaped portion; and supporting and connection means joined to said electrode structure on the remote side of the bottom portion of said first cup-shaped portion from said glass envelope portion.

7. The X-ray tube according to claim 6 wherein said cupshaped portion is formed of rolled nickel steel.

8. The X-ray tube according to claim 1 wherein said anode comprises a rotating type anode and wherein said electrode structure within the cylindrical glass portion of said envelope comprises a rotor body for said rotating type anode.

9. An X-ray tube comprising an envelope enclosing a cathode electrode and an anode electrode therewithin, said envelope including a glass portion and an electrode support structure extending within said-glass portion;

a metal portion of said envelope joined to said electrode support structure and extending from said electrode support structure for positioning said electrode support structure relative to said envelope, said metal portion comprising cold-worked metal having a distorted grain structure with a grain orientation substantially parallel to the surface of such metal portion; and

means providing a seal with said envelope portion for joining said metal portion to the glass portion of said envelope.

UNITED S'I ATES PATENT OFFICE CERTIFICATE OF CORRECTION Pate 3. 5664473 Dated February 23, 197] Inventor(s). JOHN I PERRY et 9.1

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 53, "Cup 46" should be --Cup 56--;

" line 54, before "42" insert --cup-; line 62, after "glass-to-metal" insert --sea1-.

Signed and sealed this 25th day of May 1 971 (SEAL) Attest:

EDWARD M.FLETGHER,JR. WILLIAM E. SCHUILER, JR. Atteating Officer Commissioner of Patents FORM Po-wso (10-59) USCOMWDC 

1. An X-ray tube comprising an enveloPe enclosing a cathode electrode and an anode electrode therewithin, said envelope including a cylindrical glass portion, and electrode support structure extending within said cylindrical glass portion; a metal cup-shaped portion joined to said electrode support structure and extending longitudinally from a location proximate one end of said electrode support structure for positioning said electrode support structure relative to said envelope, said cup-shaped portion comprising cold-worked metal having a distorted grain structure with a grain orientation substantially parallel to the surface of the cup-shaped portion; and means joining said metal cup-shaped portion to the cylindrical glass portion of said envelope providing a seal with said cylindrical glass envelope portion, said cup-shaped portion cooperating to form an additional closed part of said envelope.
 2. The X-ray tube according to claim 1 wherein said cup-shaped portion is a deep drawn metal cup.
 3. The X-ray tube according to claim 1 wherein said means joining said cup-shaped portion to the cylindrical portion of the envelope comprises a second cup of greater diameter than the first mentioned cup-shaped portion, being joined to the first mentioned cup-shaped portion proximate one end of said second cup and providing a glass-to-metal seal with the cylindrical glass envelope portion at its other end.
 4. The X-ray tube according to claim 1 wherein said cup-shaped portion includes a bottom portion and a cylindrical sidewall portion, said electrode structure extending through and closing an aperture provided in said bottom portion; and support and connection means joined to said electrode structure on the remote side of said bottom portion from the interior of said envelope.
 5. The X-ray tube according to claim 1 wherein said cup-shaped portion includes a bottom portion joined to said electrode structure and a cylindrical sidewall portion extending longitudinally away from said glass envelope portion defining an opening periphery at the remote end of said cup-shaped portion from said bottom portion; said means joining said cup-shaped portion to said cylindrical glass portion of said envelope comprising a second cup larger in diameter than said first cup-shaped portion, said second cup being provided with a cylindrical sidewall portion and an apertured bottom portion where said second cup is heliarc welded to the sidewall portion of said first cup-shaped portion proximate to the end of said first cup-shaped portion farthest from said glass envelope portion, the cylindrical sidewall portion of said second cup extending toward said glass envelope portion and forming a glass-to-metal seal with said glass portion of said envelope.
 6. The X-ray tube according to claim 5 wherein the bottom portion of the first cup-shaped portion is apertured with said electrode structure extending through and substantially filling said aperture, said electrode structure further extending coaxially of the sidewall portion of said first cup-shaped portion; and supporting and connection means joined to said electrode structure on the remote side of the bottom portion of said first cup-shaped portion from said glass envelope portion.
 7. The X-ray tube according to claim 6 wherein said cup-shaped portion is formed of rolled nickel steel.
 8. The X-ray tube according to claim 1 wherein said anode comprises a rotating type anode and wherein said electrode structure within the cylindrical glass portion of said envelope comprises a rotor body for said rotating type anode.
 9. An X-ray tube comprising an envelope enclosing a cathode electrode and an anode electrode therewithin, said envelope including a glass portion and an electrode support structure extending within said glass portion; a metal portion of said envelope joined to said electrode support structure and extending from said electrode support structure for positioning said electrode support structure relative to sAid envelope, said metal portion comprising cold-worked metal having a distorted grain structure with a grain orientation substantially parallel to the surface of such metal portion; and means providing a seal with said envelope portion for joining said metal portion to the glass portion of said envelope. 